Competitive Ratio. Online algorithms are typically measured by the competitive ratio [1]}. Given a sequence \(\mathbb {V}\)  of online trucks that can offer rides to the UAV, denote by \(\xi _{\rm ALG}(\mathbb {V})\)  and \(\xi _{\rm OPT}(\mathbb {V})\)  the UAV's arrival time to the destination by an online algorithm (ALG) and the optimal offline solution (OPT) where complete information of \(\mathbb {V}\)  is given beforehand, respectively. Then, the competitive ratio \(\rho \)  of the problem is defined as \(\rho =\max \limits _{\mathbb {V}}\frac{\xi _{\rm ALG}(\mathbb {V})}{\xi _{\rm OPT}(\mathbb {V})}\) . When a number \(\theta \ge 1\)  satisfies \(\theta \le \rho \)  for all deterministic online algorithms, we say \(\theta \)  is a lower bound on the competitive ratio of the problem.
